American coalition warplanes killed 21 civilians in 9 separate strikes in Iraq and Syria, the US Central Command has confirmed following the latest round of investigations, which brings the officially acknowledged casualty total to 220 since 2014.

In January, the Combined Joint Task Force received 27 new reports of civilian casualties in US-led coalition strikes against Islamic State (IS, formerly ISIS/ISIL). At the same time, it completed reviews on 19 reports, ten of which were assessed and dismissed as “non-credible.”

“Nine reports were assessed to be credible resulting in the unintended death of 21 and injury to two civilians,” CENTCOM said. A further 19 reports, some of which have been carried over from previous months, are still open and being assessed.

The new casualty figures released by CENTCOM on Saturday bring the official civilian death toll of the US-led campaign, which began under the Barack Obama administration in 2014, to 220 people.

“Although the Coalition takes extraordinary efforts to strike military targets in a manner that minimizes the risk of civilian casualties, in some incidents casualties are unavoidable,” the statement said.

The US command also noted that it could not investigate all reports of possible civilian casualties using “traditional investigative methods,” which involves interviewing witnesses and examining the site of the strike.

Instead, the coalition interviewed pilots and servicemen that took part in combat missions to draw results. The US command also reviewed strike surveillance videos and analyzed government and non-governmental organizations’ traditional and social media content.

The US army declared estimates of 220 casualties fall far below the number voiced by some monitoring groups. The Airwars monitoring group, reckons that at least 2,463 civilians have been killed by coalition air strikes, according to Reuters.

Amnesty International’s figures - which last year claimed that at least 300 civilians were killed in just 11 airstrikes conducted by the US-led coalition in Syria alone - sharply contradicts Washington’s assessment as well.

“We fear the US-led coalition is significantly underestimating the harm caused to civilians in its operations in Syria,” said Lynn Maalouf, Deputy Director for Research at Amnesty International’s Beirut regional office, at the time.

Last month, a Military Times investigation revealed that the US Central Command has also been misleading the public when it failed to account for nearly 6,000 strikes dating back to 2014, when the US-led coalition launched its first airstrikes against IS terrorist targets.